Gauge Question

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olddman

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Just finished doing the MAD change over on my 65 Dart. Now I have a problem with the fuel and temp. gauge not working. Dash lights are working and engine starts. Checked both sides of the fuse with test light and light does not come on. Dropped fuse block down and rechecked feed wire for instruments and test light does not come on. All other connections on fuse block are hot. Would like some suggestions/help as to what to do now.
 
When you did the MAD upgrade, you may have disturbed the factory splice in the black wire from the ammeter. One of the wires in the splice goes to the voltage limiter for the gas and temp gauges. The limiter is built in to the gas gauge and provides 5 volts for the gas and temp gauges to function correctly. OR possibly the limiter decided to take a dump.

Edit: I misspoke about the splice and the wire to the voltage limiter. I was looking at the wrong in harness splice! See my follow-up post
 
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I pulled gauge cluster out and made modifications to the space where the amp meter is so that a voltage gauge would fit. Reinstalled cluster and gauges worked. Now they just sit there!! Can you tell me where the splice is located? Shouldn't I have current going to fuse block from accessory side of ignition switch? Also connected the amp meter wires together. Just at a loss right now. Thanks!!
 
There is a instrument voltage limiter somewhere. Its either plugged into the circuit board backside of the inst' panel or inside a 3 post fuel gauge. It takes 12 volts in and supplies a pulse voltage out to the thermal gauges. This limiters 12 volt supply is not fused. Its supply comes directly from the ignition switch. The same blue wire from ignition switch supplies spark ignition etc... so this problem wouldn't be the ignition switch. It sounds like your limiter has suddenly stopped working.
So now my questions.... Does your fuel gauge have 3 contact posts?
If yes, did you remove this gauge any time during your mod work?
If your limiter is plugged into the circuit board, Did you remove it? If yes did you plug it back in along with the extra little male spade from noise cap' at middle post the limiter into the board? To leave that out can create a loose connection.
 
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OK I pull my FSM out as I was going from a not so good memory on my previous post. There are several splices within the harness that all work in conjunction with each other in one way or another. The main splice is around 3 to 6 inches from the 12 gauge black ammeter wire terminal end. A 2nd 12 gauge black wire goes to the firewall junction block, a 3rd 14 gauge red with tracer goes to the fuse box for all the hot all the time stuff - like the lighter and the last is a 12 gauge red wire going to the battery side of the ignition switch. So when the ignition switch is turned to either Accessory or in the Run (but not start position), it sends power to the 2nd splice within the harness. The wires from this splice goes to the (1) gauge voltage limiter, (2) to the Accessory side of the fuse box - like the radio and heater, (3) turn signal flasher, and the (4th and last wire) to the wiper switch.
I pulled gauge cluster out and made modifications to the space where the amp meter is so that a voltage gauge would fit. Reinstalled cluster and gauges worked. Now they just sit there!!

So you reinstall the gauge cluster and everything worked. Then all of a sudden they stopped working. The cluster is grounded through the mounting screws so take a look at that.

Can you tell me where the splice is located? Shouldn't I have current going to fuse block from accessory side of ignition switch? Also connected the amp meter wires together. Just at a loss right now. Thanks!!

Yes, there should be current from the Accessory side of the ignition switch to the Accessory part of the fuse box as I described above and only when the ign switch is in Acc or Run. Also In the Accessory or Run there should be power to the gauge limiter, and wiper switch. So working backwards, do your wipers work or is there power to the Acc part of the fuse box (radio/ heater work?). Do you have power to that stuff when the ign switch is in the Run position. If not i’d Suspect a bad ignition switch or wiring plug not seated good enough. Hope this helps and sorry about my previous post.
 
I forget that early A is wired a little differently than 2nd gen' It is in fact a black wire and not blue to the limiter. My point was no fuse. The fuse marked inst' on fuse box is illumination and not the instruments. To abbreviate Illumination would be ill' ? Imagine all the "What is ill fuse?" threads. Anyway... If everything works except 2 gauges, the limiter is suspect.
 
Here is a quick picture of the wiring. The main splice is above the wiper switch and the other splice is to the left of the instrument cluster

2FE5E096-0D8B-424C-ACE2-E875F6A97DF9.jpeg
 
Thank you 65 Dartman for all the information. Will be checking off the things you mentioned. I did remove the fuel and temperature gauges along with the circuit board in order to do the modifications and repaint the cluster housing. I checked the circuit board while it was out and all of the circuits were working. The fuel gauge only has two posts. Did not find a voltage limiter mounted to the cluster when I disassembled it. If there is an exterior voltage limiter mounted somewhere, I do not know where it is, where to look or what it might look like.
 
Hmmm every 65 US Dart cluster i’ve seen has the voltage limiter within the gas gauge and would have 3 prongs. I bet @65dartcharger would be interested in this thread as he is quite the expert on 65 Darts. Strange yours has only 2. If it were externally mounted, it would be readily apparent on the circuit board. If you pull the cluster to double check everything, post pictures of the front and back - I’d be interested in seeing them
 
OK, If the limiter is inside a 3 post fuel gauge( as the drawing above shows ) that gauge will have a slither of metal on the back of it that rests against the instrument housing to provide a chassis ground path for the limiter. Without contact there the limiter will not work. All of these thermal gauges including this fuel gauge have a fiber board on the back with contact studs swedged in it. The fiber boards do warp with age. If you did remove a 3 post gauge you may have noticed a unpainted spot in the housing about the size of a quarter where the ground contact is supposed to happen.
Since the limiter did run for a while then stopped, it may very well have lost its ground.
 
It may be a couple of days before I can pull the cluster again and take some pictures. If I have time tomorrow I will start taking it apart. The gauges are the ones that were in the Dart when I bought it sixteen years ago. They worked fine until I decided to modify the cluster housing. Guess I should have just mounted an external voltage gauge!! Will get pictures as soon as I can.
 
Just finished working on my Dart gauges. Before I get into what I found, I want to thank 65 Dartman and RedFish for their help. I also have to admit that I was wrong when I said that my fuel gauge only had two posts. It has three just like y'all said. Do not know what I was thinking of, guess I was thinking of the voltage gauge as I had pulled the cluster out at least ten times trying to get it to work.
Anyhow, I started this morning around noon and finally got the gauges working like they should. All I can say is that when you are working on gauges be very careful and pay attention to what you are doing. Today I pulled the cluster another six - eight times before figuring out why the fuel gauge was not registering with key in run position. I did the checks that 65 Dartman suggested, checked the fiber board, cleaned the grounding post, cleaned the spring metal grounding strap that the third post slides into, and checked for current flow through the printed circuit board. Reinstalled gauge and plugged gauge cluster housing into dash wiring harness plug. Turned key, and fuel gauge worked!! Installed cluster housing into instrument cluster bezel, installed in dash, turned key on and fuel gauge did not work! Finally after doing this remove and install six times I had a brain storm!!!! Could it be that the fuel gauge needle was in a bind or rubbing on the gauge lens since it worked when out of the bezel?
Removed the cluster again from the bezel and took a close look at the position of the needle. It looked like the needle was angled up away form the gauge face. Took my small needle nose pliers and very carefully bent the tab at base of gauge needle until it looked to be at the same angle as the temp. gauge needle. Plugged gauges back up to check and everything looked good. Installed cluster housing back into instrument cluster bezel, plugged harness up, turned key on and gauge worked!!!! Mounted bezel back onto dash and checked gauges a couple of more times before installing the wiper switch, light switch, and ignition switch. I then turned the key on a couple more times and surprise, surprise the gauge still worked.
Started engine and guess what, the temp. gauge wasn't working. What now? Did I pull the cluster again? No, I remembered that I had changed out the temperature sending unit and thought I might not have connected the wire up. Sure enough, I had forgotten to hook the gauge wire up.
What did I learn from this escapade? Take your time, be careful when working on delicate parts, check your work and if you still have a problem come here and someone will help you out!!!!!
Again thanks.
 
Glad you found the problem. Let's hope that mechanical limiter continues to work for a long time.
Not all gauge needles are so easily distorted in handling. You found your needles to be mounted on pivot posts like a shirt pin passing through 2 holes in needle base. All that needs to stay perfectly aligned so needle moves freely. Bend it and the needle may drag and/or jump as it moves.
Other owners will find their gauge needles have no pivot posts. Instead, they are suspended between 2 hooks. Even though it is a much lighter, more delicate needle to handle, paint, etc.., its movement isn't so easily screwed up.
 
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